1. Field of the invention
The present invention relates to the manufacture of composite components comprising a web and a reinforcement structure. More particularly, the invention relates to a process for the manufacture of composite material components comprising a rigid web, such as a sheet or thin plate having a specific shape, provided on at least one of its faces with a reinforcement structure that is unitary with the web and designed to provide the components with the stiffness and mechanical properties required for their use.
One particular application of the invention is in the manufacture of composite internal flaps of turbojet nozzles, such flaps comprising a web having a reinforcement structure, which can he "H" shaped, on one of their faces.
A composite material component is made from a fibrous texture that is densified by a matrix. The materials constituting the fibrous texture and the matrix are selected as a function of the component's conditions of use. With composite components that are exposed to high thermo-mechanical stresses, such as in the case of internal flaps for turbojet nozzles, the materials used are typically made from a carbon or silicon carbidefibrous texture in combination with a carbon or ceramic matrix, usually made of silicon carbide.
2. Prior art
One known method for manufacturing a component having a complex shape consists in making preforms of constituent parts of the component having simple shapes, and then assembling the preforms, e.g. by molding with a themoformable resin, to produce a preform of the final component, and finally densifying the thus-obtained preform with matrix material, as the thermoformable resin is eliminated.
This known method has been implemented by the applicant for the manufacture of flaps for turbojet nozzles, of the type shown in figure . The preform of the web is made by piling layers of a bidimensional fibrous texture, such as a fabric. The preform for the reinforcement structure 2 is made by piling layers of a bidimensional fibrous texture to form a plate, fixing the shape of the plate by impregnation with thermoformable resin and machining an "H" shaped reinforcement from the plate whose shape has thus been fixed. The preforms for the web and reinforcement structure are assembled in a mold to obtain a preform for a flap by molding with a thermoformable resin. During the molding operation, the web is conformed as shown in FIG. 1, so as to obtain the desired relief, produce ear or leg elements 3 , and draw the web and reinforcement structure into perfect mutual contact. The densification of the preform for the flap, which is held inside a tool, is achieved by vapor-phase infiltration of matrix material, e.g. silicon carbide within the fibrous texture, the thermoformable resin e.g. being eliminated during the temperature rise preceding the infiltration of the matrix. During assembly, the flap is affixed to the end of an actuator that conveys the desired movements to the flap, as well as to two adjacent flaps that press against the legs 3.
It appeared that this method could have some drawbacks. For instance, it turned out that the web could separate from the reinforced structure when the flap was in use. Besides, the complexity of the molds makes this method expensive and ill adapted to series production.
It is therefore an object of the present invention to provide a process for producing composite components, comprising a web and a reinforcement structure, that is free of the above-mentioned risk of separation between the web and reinforcement, while offering a reduced manufacturing cost in series production.